SkTextBlob: Begin implementing Extended TextBlob API

src/core/SkTextBlob.cpp

Index: src/core/SkTextBlob.cpp
diff --git a/src/core/SkTextBlob.cpp b/src/core/SkTextBlob.cpp
index 3c7345f9a04df85e8b816fc21b7dbddaeff40d64..35adc24a34ff6610aa335d542c04c89f040c3291 100644
--- a/src/core/SkTextBlob.cpp
+++ b/src/core/SkTextBlob.cpp
@@ -105,17 +105,41 @@ static_assert(sizeof(RunFont) == sizeof(RunFontStorageEquivalent), "runfont_shou
 //
 //  Each run record describes a text blob run, and can be used to determine the (implicit)
 //  location of the following record.
+//
+// Extended Textblob runs have more data after the Pos[] array:
+//
+//    -------------------------------------------------------------------------
+//    ... | RunRecord | Glyphs[] | Pos[] | TextSize | Clusters[] | Text[] | ...
+//    -------------------------------------------------------------------------
+//
+// To determine the length of the extended run data, the TextSize must be read.
+//
+// Extended Textblob runs may be mixed with non-extended runs.
 
 SkDEBUGCODE(static const unsigned kRunRecordMagic = 0xb10bcafe;)
 
+namespace {
+struct RunRecordStorageEquivalent {
+    RunFont  fFont;
+    SkPoint  fOffset;
+    uint32_t fCount;
+    uint32_t fFlags;
+    SkDEBUGCODE(unsigned fMagic;)
+};
+}
+
 class SkTextBlob::RunRecord {
 public:
-    RunRecord(uint32_t count, const SkPoint& offset, const SkPaint& font, GlyphPositioning pos)
+    RunRecord(uint32_t count, uint32_t textSize,  const SkPoint& offset, const SkPaint& font, GlyphPositioning pos)
         : fFont(font)
         , fCount(count)
         , fOffset(offset)
-        , fPositioning(pos) {
+        , fPositioning(pos)
+        , fExtended(textSize > 0) {
         SkDEBUGCODE(fMagic = kRunRecordMagic);
+        if (textSize > 0) {
+            *this->textSizePtr() = textSize;
+        }
     }
 
     uint32_t glyphCount() const {
@@ -135,7 +159,8 @@ public:
     }
 
     uint16_t* glyphBuffer() const {
-        // Glyph are stored immediately following the record.
+        static_assert(SkIsAlignPtr(sizeof(RunRecord)), "");
+        // Glyphs are stored immediately following the record.
         return reinterpret_cast<uint16_t*>(const_cast<RunRecord*>(this) + 1);
     }
 
@@ -145,11 +170,31 @@ public:
                                            SkAlign4(fCount * sizeof(uint16_t)));
     }
 
-    static size_t StorageSize(int glyphCount, SkTextBlob::GlyphPositioning positioning) {
+    uint32_t textSize() const { return fExtended ? *this->textSizePtr() : 0; }
+
+    uint32_t* clusterBuffer() const {
+        // clusters follow the textSize.
+        return fExtended ? 1 + this->textSizePtr() : nullptr;
+    }
+
+    char* textBuffer() const {
+        if (!fExtended) { return nullptr; }
+        return reinterpret_cast<char*>(this->clusterBuffer() + fCount);
+    }
+
+    static size_t StorageSize(int glyphCount, int textSize,
+                              SkTextBlob::GlyphPositioning positioning) {
+        static_assert(SkIsAlign4(sizeof(SkScalar)), "SkScalar size alignment");
         // RunRecord object + (aligned) glyph buffer + position buffer
-        return SkAlignPtr(sizeof(SkTextBlob::RunRecord)
-                        + SkAlign4(glyphCount* sizeof(uint16_t))
-                        + glyphCount * sizeof(SkScalar) * ScalarsPerGlyph(positioning));
+        size_t size = sizeof(SkTextBlob::RunRecord)
+                      + SkAlign4(glyphCount* sizeof(uint16_t))
+                      + PosCount(glyphCount, positioning) * sizeof(SkScalar);
+        if (textSize > 0) {  // Extended run.
+            size += sizeof(uint32_t)
+                + sizeof(uint32_t) * glyphCount
+                + textSize;
+        }
+        return SkAlignPtr(size);
     }
 
     static const RunRecord* First(const SkTextBlob* blob) {
@@ -158,20 +203,41 @@ public:
     }
 
     static const RunRecord* Next(const RunRecord* run) {
-        return reinterpret_cast<const RunRecord*>(reinterpret_cast<const uint8_t*>(run)
-            + StorageSize(run->glyphCount(), run->positioning()));
+        return reinterpret_cast<const RunRecord*>(
+                reinterpret_cast<const uint8_t*>(run)
+                + StorageSize(run->glyphCount(), run->textSize(), run->positioning()));
     }
 
     void validate(const uint8_t* storageTop) const {
         SkASSERT(kRunRecordMagic == fMagic);
         SkASSERT((uint8_t*)Next(this) <= storageTop);
+
         SkASSERT(glyphBuffer() + fCount <= (uint16_t*)posBuffer());
         SkASSERT(posBuffer() + fCount * ScalarsPerGlyph(fPositioning) <= (SkScalar*)Next(this));
+        if (fExtended) {
+            SkASSERT(textSize() > 0);
+            SkASSERT(textSizePtr() < (uint32_t*)Next(this));
+            SkASSERT(clusterBuffer() < (uint32_t*)Next(this));
+            SkASSERT(textBuffer() + textSize() <= (char*)Next(this));
+        }
+        static_assert(sizeof(SkTextBlob::RunRecord) == sizeof(RunRecordStorageEquivalent),
+                      "runrecord_should_stay_packed");
     }
 
 private:
     friend class SkTextBlobBuilder;
 
+    static size_t PosCount(int glyphCount,
+                           SkTextBlob::GlyphPositioning positioning) {
+        return glyphCount * ScalarsPerGlyph(positioning);
+    }
+    
+    uint32_t* textSizePtr() const {
+        // textSize follows the position buffer.
+        SkASSERT(fExtended);
+        return (uint32_t*)(&this->posBuffer()[PosCount(fCount, fPositioning)]);
+    }
+
     void grow(uint32_t count) {
         SkScalar* initialPosBuffer = posBuffer();
         uint32_t initialCount = fCount;
@@ -189,6 +255,7 @@ private:
     uint32_t         fCount;
     SkPoint          fOffset;
     GlyphPositioning fPositioning;
+    bool             fExtended;
 
     SkDEBUGCODE(unsigned fMagic;)
 };
@@ -218,6 +285,17 @@ SkTextBlob::~SkTextBlob() {
     }
 }
 
+namespace {
+union PositioningAndExtended {
+    int32_t intValue;
+    struct {
+        SkTextBlob::GlyphPositioning positioning;
+        bool extended;
+        uint16_t padding;
+    };
+};
+} // namespace
+
 void SkTextBlob::flatten(SkWriteBuffer& buffer) const {
     int runCount = fRunCount;
 
@@ -230,7 +308,17 @@ void SkTextBlob::flatten(SkWriteBuffer& buffer) const {
         SkASSERT(it.glyphCount() > 0);
 
         buffer.write32(it.glyphCount());
-        buffer.write32(it.positioning());
+        PositioningAndExtended pe;
+        pe.intValue = 0;
+        pe.positioning = it.positioning();
+        SkASSERT((int32_t)it.positioning() == pe.intValue);  // backwards compat.
+
+        uint32_t textSize = it.textSize();
+        pe.extended = textSize > 0;
+        buffer.write32(pe.intValue);
+        if (pe.extended) {
+            buffer.write32(textSize);
+        }
         buffer.writePoint(it.offset());
         // This should go away when switching to SkFont
         it.applyFontToPaint(&runPaint);
@@ -239,6 +327,10 @@ void SkTextBlob::flatten(SkWriteBuffer& buffer) const {
         buffer.writeByteArray(it.glyphs(), it.glyphCount() * sizeof(uint16_t));
         buffer.writeByteArray(it.pos(),
             it.glyphCount() * sizeof(SkScalar) * ScalarsPerGlyph(it.positioning()));
+        if (pe.extended) {
+            buffer.writeByteArray(it.clusters(), sizeof(uint32_t) * it.glyphCount());
+            buffer.writeByteArray(it.text(), it.textSize());
+        }
 
         it.next();
         SkDEBUGCODE(runCount--);
@@ -258,10 +350,14 @@ sk_sp<SkTextBlob> SkTextBlob::MakeFromBuffer(SkReadBuffer& reader) {
     SkTextBlobBuilder blobBuilder;
     for (int i = 0; i < runCount; ++i) {
         int glyphCount = reader.read32();
-        GlyphPositioning pos = static_cast<GlyphPositioning>(reader.read32());
+
+        PositioningAndExtended pe;
+        pe.intValue = reader.read32();
+        GlyphPositioning pos = pe.positioning;
         if (glyphCount <= 0 || pos > kFull_Positioning) {
             return nullptr;
         }
+        uint32_t textSize = pe.extended ? (uint32_t)reader.read32() : 0;
 
         SkPoint offset;
         reader.readPoint(&offset);
@@ -271,13 +367,15 @@ sk_sp<SkTextBlob> SkTextBlob::MakeFromBuffer(SkReadBuffer& reader) {
         const SkTextBlobBuilder::RunBuffer* buf = nullptr;
         switch (pos) {
         case kDefault_Positioning:
-            buf = &blobBuilder.allocRun(font, glyphCount, offset.x(), offset.y(), &bounds);
+            buf = &blobBuilder.allocRunText(font, glyphCount, offset.x(), offset.y(),
+                                            textSize, SkString(), &bounds);
             break;
         case kHorizontal_Positioning:
-            buf = &blobBuilder.allocRunPosH(font, glyphCount, offset.y(), &bounds);
+            buf = &blobBuilder.allocRunTextPosH(font, glyphCount, offset.y(),
+                                                textSize, SkString(), &bounds);
             break;
         case kFull_Positioning:
-            buf = &blobBuilder.allocRunPos(font, glyphCount, &bounds);
+            buf = &blobBuilder.allocRunTextPos(font, glyphCount, textSize, SkString(), &bounds);
             break;
         default:
             return nullptr;
@@ -288,6 +386,13 @@ sk_sp<SkTextBlob> SkTextBlob::MakeFromBuffer(SkReadBuffer& reader) {
                                   glyphCount * sizeof(SkScalar) * ScalarsPerGlyph(pos))) {
             return nullptr;
         }
+
+        if (pe.extended) {
+            if (!reader.readByteArray(buf->clusters, glyphCount * sizeof(uint32_t))  ||
+                !reader.readByteArray(buf->utf8text, textSize)) {
+                return nullptr;
+            }
+        }
     }
 
     return blobBuilder.make();
@@ -350,6 +455,20 @@ void SkTextBlobRunIterator::applyFontToPaint(SkPaint* paint) const {
     fCurrentRun->font().applyToPaint(paint);
 }
 
+uint32_t* SkTextBlobRunIterator::clusters() const {
+    SkASSERT(!this->done());
+    return fCurrentRun->clusterBuffer();
+}
+uint32_t SkTextBlobRunIterator::textSize() const {
+    SkASSERT(!this->done());
+    return fCurrentRun->textSize();
+}
+char* SkTextBlobRunIterator::text() const {
+    SkASSERT(!this->done());
+    return fCurrentRun->textBuffer();
+}
+
+
 bool SkTextBlobRunIterator::isLCD() const {
     return SkToBool(fCurrentRun->font().flags() & SkPaint::kLCDRenderText_Flag);
 }
@@ -513,6 +632,10 @@ bool SkTextBlobBuilder::mergeRun(const SkPaint &font, SkTextBlob::GlyphPositioni
                                                                           fLastRun);
     SkASSERT(run->glyphCount() > 0);
 
+    if (run->textSize() != 0) {
+        return false;
+    }
+
     if (run->positioning() != positioning
         || run->font() != font
         || (run->glyphCount() + count < run->glyphCount())) {
@@ -529,8 +652,8 @@ bool SkTextBlobBuilder::mergeRun(const SkPaint &font, SkTextBlob::GlyphPositioni
         return false;
     }
 
-    size_t sizeDelta = SkTextBlob::RunRecord::StorageSize(run->glyphCount() + count, positioning) -
-                       SkTextBlob::RunRecord::StorageSize(run->glyphCount(), positioning);
+    size_t sizeDelta = SkTextBlob::RunRecord::StorageSize(run->glyphCount() + count, 0, positioning) -
+                       SkTextBlob::RunRecord::StorageSize(run->glyphCount(), 0, positioning);
     this->reserve(sizeDelta);
 
     // reserve may have realloced
@@ -553,24 +676,25 @@ bool SkTextBlobBuilder::mergeRun(const SkPaint &font, SkTextBlob::GlyphPositioni
 
 void SkTextBlobBuilder::allocInternal(const SkPaint &font,
                                       SkTextBlob::GlyphPositioning positioning,
-                                      int count, SkPoint offset, const SkRect* bounds) {
+                                      int count, int textSize, SkPoint offset, const SkRect* bounds) {
     SkASSERT(count > 0);
+    SkASSERT(textSize >= 0);
     SkASSERT(SkPaint::kGlyphID_TextEncoding == font.getTextEncoding());
-
-    if (!this->mergeRun(font, positioning, count, offset)) {
+    if (textSize != 0 || !this->mergeRun(font, positioning, count, offset)) {
         this->updateDeferredBounds();
 
-        size_t runSize = SkTextBlob::RunRecord::StorageSize(count, positioning);
+        size_t runSize = SkTextBlob::RunRecord::StorageSize(count, textSize, positioning);
         this->reserve(runSize);
 
         SkASSERT(fStorageUsed >= sizeof(SkTextBlob));
         SkASSERT(fStorageUsed + runSize <= fStorageSize);
 
         SkTextBlob::RunRecord* run = new (fStorage.get() + fStorageUsed)
-                                         SkTextBlob::RunRecord(count, offset, font, positioning);
-
+            SkTextBlob::RunRecord(count, textSize, offset, font, positioning);
         fCurrentRunBuffer.glyphs = run->glyphBuffer();
         fCurrentRunBuffer.pos = run->posBuffer();
+        fCurrentRunBuffer.utf8text = run->textBuffer();
+        fCurrentRunBuffer.clusters = run->clusterBuffer();
 
         fLastRun = fStorageUsed;
         fStorageUsed += runSize;
@@ -579,7 +703,8 @@ void SkTextBlobBuilder::allocInternal(const SkPaint &font,
         SkASSERT(fStorageUsed <= fStorageSize);
         run->validate(fStorage.get() + fStorageUsed);
     }
-
+    SkASSERT(textSize > 0 || nullptr == fCurrentRunBuffer.utf8text);
+    SkASSERT(textSize > 0 || nullptr == fCurrentRunBuffer.clusters);
     if (!fDeferredBounds) {
         if (bounds) {
             fBounds.join(*bounds);
@@ -589,26 +714,31 @@ void SkTextBlobBuilder::allocInternal(const SkPaint &font,
     }
 }
 
-const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRun(const SkPaint& font, int count,
-                                                                SkScalar x, SkScalar y,
-                                                                const SkRect* bounds) {
-    this->allocInternal(font, SkTextBlob::kDefault_Positioning, count, SkPoint::Make(x, y), bounds);
-
+const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRunText(const SkPaint& font, int count,
+                                                                    SkScalar x, SkScalar y,
+                                                                    int textByteCount,
+                                                                    SkString lang,
+                                                                    const SkRect* bounds) {
+    this->allocInternal(font, SkTextBlob::kDefault_Positioning, count, textByteCount, SkPoint::Make(x, y), bounds);
     return fCurrentRunBuffer;
 }
 
-const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRunPosH(const SkPaint& font, int count,
-                                                                    SkScalar y,
-                                                                    const SkRect* bounds) {
-    this->allocInternal(font, SkTextBlob::kHorizontal_Positioning, count, SkPoint::Make(0, y),
+const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRunTextPosH(const SkPaint& font, int count,
+                                                                        SkScalar y,
+                                                                        int textByteCount,
+                                                                        SkString lang,
+                                                                        const SkRect* bounds) {
+    this->allocInternal(font, SkTextBlob::kHorizontal_Positioning, count, textByteCount, SkPoint::Make(0, y),
                         bounds);
 
     return fCurrentRunBuffer;
 }
 
-const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRunPos(const SkPaint& font, int count,
-                                                                   const SkRect *bounds) {
-    this->allocInternal(font, SkTextBlob::kFull_Positioning, count, SkPoint::Make(0, 0), bounds);
+const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRunTextPos(const SkPaint& font, int count,
+                                                                       int textByteCount,
+                                                                       SkString lang,
+                                                                       const SkRect *bounds) {
+   this->allocInternal(font, SkTextBlob::kFull_Positioning, count, textByteCount, SkPoint::Make(0, 0), bounds);
 
     return fCurrentRunBuffer;
 }
@@ -631,7 +761,8 @@ sk_sp<SkTextBlob> SkTextBlobBuilder::make() {
         size_t validateSize = sizeof(SkTextBlob);
         const SkTextBlob::RunRecord* run = SkTextBlob::RunRecord::First(blob);
         for (int i = 0; i < fRunCount; ++i) {
-            validateSize += SkTextBlob::RunRecord::StorageSize(run->fCount, run->fPositioning);
+            validateSize += SkTextBlob::RunRecord::StorageSize(
+                    run->fCount, run->textSize(), run->fPositioning);
             run->validate(reinterpret_cast<const uint8_t*>(blob) + fStorageUsed);
             run = SkTextBlob::RunRecord::Next(run);
         }